Wireless networks (i.e., cellular and/or other like mobile networks) are generally known in the telecommunication arts. In a typical example, a mobile station (MS), e.g., such as a mobile or cellular telephone or other like end user device or terminal, is provided access to the wireless network via a radio frequency (RF) or other suitable over-the-air (OTA) interface. More specifically, a typical wireless network is generally made up of a plurality of base stations that are capable of wirelessly exchanging RF or other suitable signals and/or communications with one or more mobile stations. Each base station (BS) generally serves a corresponding geographic area, e.g., which is commensurate in scope with the normal operative range of the BS. The geographic area served by a BS is commonly known as a “cell.” As is generally known in the art, each BS normally provides the aforementioned RF or other OTA interface to the MS when the MS is located within the cell served by the particular BS.
With reference to FIG. 1, there is illustrated an exemplary wireless network 10 including a plurality of cells each served by a respective BS (not shown in FIG. 1). As illustrated, an individual cell is indicated generally by a corresponding hexagonal area. Typically, each cell employs a pair of control channels and a plurality of voice or traffic channels that make up the OTA interface provided in that cell. The control channels are generally used to exchange call set-up, registration and/or other like control signaling between the BS and MS. The one control channel typically used to transmit control signaling from the BS to the MS is generally referred to merely as the control channel or the forward control channel, and the other control channel typically used to transmit control signaling from the MS to the BS is generally referred to as the reverse control channel. The plurality of voice or traffic channels are generally used to exchange call traffic between the BS and MS. Within a given cell, the channels are conventionally defined and/or distinguished by different frequencies that are assigned or designated for the various channels. Accordingly, each cell employs a set of distinct frequencies that define and/or distinguish the different channels established therein.
Generally, to prevent interference between cells, adjacent or nearby cells employ different frequency sets for their respective channels. However, the frequency sets are typically reused periodically by sufficiently spaced apart cells. For example, the cell 20 may employ a first set of frequencies that define and/or distinguish the respective channels used in cell 20. Accordingly, the cell 30 employs a second set of frequencies (different from the first set) that define and/or distinguish the respective channels used in cell 30; the cell 31 employs a third set of frequencies (different from the first and second sets) that define and/or distinguish the respective channels used in cell 31; the cell 32 employs a fourth set of frequencies (different from the first, second and third sets) that define and/or distinguish the respective channels used in cell 32; and so on for the cells 33, 34 and 35. However, as cell 40 is sufficiently spaced apart from cell 20, the cell 40 may reuse the first set of frequencies to define and/or distinguish the respective channels used in cell 40.
Additionally, with reference now to FIG. 2, the BS 22 serving each cell is generally equipped or otherwise provisioned to selectively vary the power level used to sent transmissions over particular channels within the cell served by the BS 22. For example, the BS 22 is typically able to employ a plurality of different transmission powers levels on a channel-by-channel basis. That is to say, the BS 22 may use a first power level for transmissions being sent over a first channel, while using a second power level (different from the first power level) for transmissions being sent over a second channel (different from the first channel). In this way, the BS 22 is able to adjust the transmission power level used in particular instances, e.g., based upon a detected proximity of an MS for which a given transmission is intended. For example, if a transmission is intended for an MS 50 (which is relatively close to the BS 22), then the power level for that transmission is selected or otherwise set relatively low. Conversely, if a transmission is intended for an MS 52 (which is relatively far from the BS 22), then the power level for that transmission is selected or otherwise set relatively high.
Likewise, the MS is also typically equipped or otherwise provisioned to transmit at a variety of different power levels. Normally, the MS selects or otherwise sets its transmission power level based upon a signal received from the BS serving the MS. For example, the aforementioned signal commonly serves as a request, command or instruction from the BS for the MS to transmit at a particular selected power level based upon a detected proximity of the MS to the BS serving that MS.
In a typical example, wireless network operators or the like adopt and/or implement an intercellular interference plan that regulates the different transmission power levels used by base stations and mobile stations under normal operating conditions. That is to say, generally the intercellular interference plan dictates the different transmission power levels to be used by the various base stations and mobile stations in particular circumstances based upon one or more factors, e.g., such as the location and/or topology of the cell in which the BS and/or MS resides, the distance between the BS and the MS being served by the BS, the relative proximity of the BS and/or MS to other cells, etc.
Commonly, in accordance with the intercellular interference plan, the transmission power levels used by the BS 22 under normal operating conditions are typically less than a maximum power level at which the BS 22 is capable of transmitting. In this way, the effective range of transmissions from the BS 22 is normally limited to the cell being served by the BS 22. Additionally, limiting the transmission power levels normally used to something less than the maximum level at which the BS 22 is capable of transmitting guards against interference with other cells that may be using the same set of frequencies for their channels. Similarly, minimizing the transmission power level used by the MS during normal operation, while still assuring that transmissions from the MS are powerful enough to reach the BS currently serving the MS, aids in extending a battery life of the MS and limits the potential for interference with other cells. Therefore, traditional intercellular interference plan are also typically designed to regulate MS transmission power levels accordingly.
Collectively, the combination of cells within a network generally define the normal “service area” of the wireless network, i.e., the geographic area in which the MS is normally provided access to the wireless network. As can be appreciate, when the MS is located within the normal geographic boundaries of the service area (SA), it may selectively access the wireless network, e.g., via the RF or other OTA interface provided by the BS serving the cell in which the MS is located. Conversely, when the MS is outside the normal geographic boundaries of the SA, it is generally not able to access the wireless network insomuch as the MS is outside of any cell served by a BS of the wireless network—that is to say, the MS is generally out of the usual range of any suitable network BS and therefore cannot utilize any corresponding RF or other OTA interface which would normally be provided by the BS. Typically, when an MS exits the normal SA of a wireless network and/or is no longer registered with the wireless network, the MS will display a suitable notification (e.g., such as “No Signal” or “Out of Service Area” or “Network Not Found” or the like) and will not allow a user to place a call with the MS or will otherwise not attempt to access the wireless network.
Nevertheless, in certain instances the MS may be just outside the normal SA of the network but otherwise nearby, and a user may at times still desire to place a call or otherwise access the wireless network. This is particularly true in the case of an emergency, e.g., such as when the user desires to place an emergency 9-1-1 call or utilize a service such as GETS (Government Emergency Telecommunication Service) or WPS (Wireless Priority Service). However, conventional mobile stations and/or wireless networks are not equipped or otherwise provisioned to effectively attempt completion of such calls when the MS is outside the normal SA of the wireless network. Accordingly, to place such a call or utilize such a service, the user conventionally had to move into the normal SA of the wireless network. This is not, however, always an option. For example, for whatever reason, the user may be unable to move or reach the normal SA or may be uncertain of its direction from their current location.
Accordingly, a new and improved wireless telecommunications system and/or method is disclosed that overcomes the above-referenced problems and others.